In at least some known integrated gasification combined cycle systems (IGCC), carbon dioxide (and, more generally, carbon dioxide-rich gas) removed from syngas is vented or is used for the production of chemicals, and is typically not recycled to the gasifier (also referred to herein as gasification reactor). In those systems wherein carbon dioxide-rich gas has been recycled back to the gasifier (i.e., in some gaseous feedstock plants and a few liquid feedstock plants), the recycling has been performed to increase the carbon monoxide to hydrogen ratio in the syngas for processes generating oxo-chemicals. However, in such processes, no benefits have been achieved with regard to reduced oxygen consumption or improved carbon conversion with a gaseous feedstock.
A need exists for improving IGCC efficiency with respect to processing of carbon dioxide-rich gas in an IGCC plant. Specifically, a need exists for a gasification method that has a reduced oxygen and/or hydrogen consumption, and that has an increased carbon conversion. Additionally, it would be advantageous if cooling methods could be provided that required a lower heating value as compared to conventional methods, thereby providing for a more cost-efficient and economical alternative.